Apr 25, 2017 02:03 PM EDT
Engineers from the Massachusetts Institute of Technology have discovered that graphene is able to hold up under high pressure. This strong, ultrathin material may be the solution in making desalination more productive.
A single sheet of graphene is comprised of an atom-thin lattice of carbon which may seem fragile but can withstand applied pressures of at least 100 bars. This is equivalent to about 20 times the pressure produced by a kitchen faucet.
In a post on its official website, MIT reported that the reason why graphene can withstand intense pressures is to pair it with a thin underlying support substrate that has tiny holes or pores. The smaller these pores are, the more resilient the material is under high pressure.
Rohit Karnik, an associate professor in MIT's Department of Mechanical Engineering, said that the study will serve as a guideline for developing tough, graphene-based membranes. This can be used specifically for desalination, where filtration membranes should withstand high-pressure flows to efficiently remove salt from seawater.
It was noted that current existing membranes desalinate water through reverse osmosis. This is when pressure is applied to one side of a membrane containing saltwater and pushes pure water across the membrane while salt as well as other molecules are hindered from filtering through.
Several commercial membranes desalinate water under pressures of about 50 to 80 bars. Anything above that and they tend to get compacted or otherwise suffer in performance.
Using graphene which can withstand pressure of 100 bars or more could lead to more effective desalination of seawater by recovering more fresh water. It is expected to solve the fresh water crisis by having the ability to purify extremely salty water.
The MIT engineers set up experiments to investigate graphene's pressure tolerance. They grew sheets of graphene through a technique named chemical vapor deposition and placed single layers of the material on thin sheets of porous polycarbonate. They discovered that graphene was able to withstand pressures of 100 bars when placed over pores that were 200 nanometers wide or smaller.
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